Suttles said workers also are sampling bubbles visible around the wellhead to assure they are not an indication of leaking of oil or natural gas from the well.

Initial tests indicate the bubbles are not hydrates -- a solid form of methane or natural gas formed by the combination of cold temperatures and pressures a mile below the water's surface -- but that additional tests must be completed to confirm that conclusion.

"If you can imagine, it is not an easy operation to collect those bubbles so that they can be tested to see what their make-up is," he said.

As reported earlier today, methane bubbles are a likely indicator that heavier oil is on the way.. and exactly what experts are looking for with newly-arrived sensing devices. See: